I just sent a new Bisson Pitts in that was on a hard mounted ZDZ50 for only 5 minutes run time...

I noticed some fo that "new engine black" on the muffler and upon closer inspection found a "micro" crack about 1/16 along the seem of the box...

Without a doubt a defect like this would result in a muffler breaking off... I could be the ones that fail sooner have these little weld defects, and are destined for doom....

I suggest checking it carefully after the first run for just such an indicator...